Energy storage flywheel

Abstract

A flywheel comprising a rim (1) which is a substantially circular ring mounted on a central portion (2) which central portion comprises at least one substantially circular dished member which has a specific modulus which is less than the specific modulus of the rim, the dished member being curved such that increasing rotational speed tends to elastically deform the dished member, straightening the curve, thereby increasing the diameter of the dished member. In a preferred embodiment, the central portion (2) comprises at least two co-axial dished members (3,4) which are imperforate apart from a central hole (5), each dished member comprising three integrally formed annular portions, two of the portions (6,8) being curved and being positioned on each side of the third portion which is straight or curved.

I claim: 
     
       1. A flywheel comprising a rim which is a substantially circular ring mounted on a central portion, the central portion comprising at least one substantially circular solid disc which is imperforate except for a central hole and which comprises three integrally formed annular portions, two of the portions being curved and being positioned on each side of the third annular portion, the radii of the curved portions being such that the diameter of the solid disc tends to increase with increasing rotational speed and the specific modulus of the solid disc being less than the specific modulus of the rim. 
     
     
       2. A flywheel as in claim 1 in which the central portion of the flywheel comprises two or more coaxial, solid discs. 
     
     
       3. A flywheel as in claim 1 in which each solid disc comprises three integrally formed annular curved portions. 
     
     
       4. A flywheel as in claim 3 in which the curves of the curved portions are arcs of circles. 
     
     
       5. A flywheel as in claim 1 in which the specific modulus of each of the solid discs is from 25 to 70% of the specific modulus of the rim. 
     
     
       6. A flywheel as in claim 1 in which each solid disc comprises two annular curved portions having radii smaller than the radius of the third annular curved portion positioned between the curved portions of smaller radii. 
     
     
       7. A flywheel as in claim 6 in which the radii of the two curved portions having the smaller radii are the same or different and are from 0.002 times the diameter of the solid disc. 
     
     
       8. A flywheel as in claim 6 in which the radius of the curved portion having the larger radius is from 0.3 to 1.0 times the diameter of the solid disc. 
     
     
       9. A flywheel as in claim 7 in which the radius of the curved portion having the larger radius is from 0.3 to 1.0 times the diameter of the solid disc. 
     
     
       10. A flywheel as in claim 1 in which the radius (r 2 ) of the curved portio adjacent the central hole of the solid disc is from 1 to 3 times the radius (r 1 ) of the curved portion adjacent the periphery of the solid disc. 
     
     
       11. A flywheel as in claim 1 in which the center of curvature of the curved portion adjacent the periphery of the solid disc and the center of curvature of the curved portion adjacent the central hole of the solid disc lie on different planes, which planes are pependicular to the rotational axis of the flywheel. 
     
     
       12. A flywheel as in claim 1 in which the ratio of the diameter of the central hole in the solid discs to the diameter of the solid discs is from 0.2 to 0.6. 
     
     
       13. A flywheel as in claim 1 in which the diameter of the solid disc is from 0.01% smaller to 0.05% larger than the internal diameter of the rim. 
     
     
       14. A flywheel as in claim 1 in which the central portion is fixed to the rim using an adhesive joint. 
     
     
       15. A flywheel as in claim 1 in which the ratio of the inner radius of the rim to the outer radius of the rim is from 0.6:1 to 0.85:1. 
     
     
       16. A flywheel as in claim 1 in which the third annular portion is straight.